The primary function of an electrical connector is to provide electrical connection from one electronic device to another so that data signals may be electrically communicated between the two devices. In an ideal situation, a data signal that exits the connector at one end of the connector should be free of distortion and resemble the data signal as it enters the connector at the other end.
FIG. 1 illustrates a lengthwise cross-sectional view of one example of a connector 100 which has two lengthwise extending structures 201, 211 upon each of which a reference voltage conductor is provided on one side and a pair of data signal conductors is provided on the other side. Although only two such structures 201, 211 are shown, it is to be appreciated that many more of such lengthwise extending structures may be provided in the connector 100 to accommodate more data signal conductors.
The data signal conductors are used to transmit data signals from one end of the connector 100 to the other. The reference voltage conductors (i.e., power and ground) provide current return paths for the data signals transmitted through the data signal conductors. Outside the connector 100, such as on printed circuit boards 111 and 112 to which the connector 100 has been connected, all of the high reference voltage conductors of the same voltage level are connected to a common high voltage reference (e.g., power) and all of the low reference voltage conductors are connected to a common low voltage reference (e.g., ground).
FIGS. 2a and 2b respectively illustrate simplified top and bottom views of the lengthwise extending structure 201. As shown in FIG. 2a, the structure 201 has a voltage reference conductor 202 that covers most of one large area side of the structure 201 and as shown in FIG. 2b, the structure 201 has a pair of data signal conductors 203, 204 extending lengthwise on the opposite large area side of the structure 201. Although only two data signal conductors 203, 204 are shown on one side of the structure 201 in this example, more than two data signal conductors may also be provided. The second lengthwise extending structure 211 is similarly constructed as the first structure 201. The structures 201, 211 are generally non-conductive supporting structures that are separated, as shown in their respectively lengthwise and widthwise cross-sectional views in FIGS. 3a and 3b, by an air gap or non-conductive filler material 280 (such as a plastic).
Referring back to FIG. 1, the connector 100 is a two-part connector having a first part 101 connected to a first printed circuit board 111 and a second part 102 connected to a second printed circuit board 112. This two-part structure is advantageous, for example, because it facilitates wave-soldering the first and second parts 101, 102 respectively to the first and second printed circuit boards 111, 112. For example, as shown in FIG. 1, leads on the first part 101 that are connected to the voltage reference conductors 202, 212 and data signal conductors 203, 204, 213, 214 are soldered to the printed circuit board 111; and mating structures on the second part 102 are soldered to the printed circuit board 112. To subsequently connect the first and second printed circuit boards 111, 112 together so that data signals may be transmitted from one to the other, the first and second parts 101, 102 of the connector 100 are mechanically mated together. In particular, edges 205, 215 of the lengthwise extending structures 201, 211 serve as male members on the first part 101 that press fit into pairs of opposing clips (acting as mating structures) provided on the second part 102.
More particularly, to mate with edge 205 of the structure 201, a clip 252 makes physical and electrical connection with the voltage reference conductor 202 and its opposing clip 253 makes physical and electrical connection with the data signal conductor 203 so that the opposing clips 252, 253 apply a holding force to the edge 205 of the structure 201. Another pair of opposing clips (occluded from view and not shown in FIG. 1) is also provided wherein one of the clips makes physical and electrical connection with the voltage reference conductor 202 and the other of the clips makes physical and electrical connection with the data signal conductor 204 so that the opposing clips also apply a holding force to the edge 205 of the structure 201.
Likewise, to mate with edge 215 of the structure 211, a clip 262 makes physical and electrical connection with the voltage reference conductor 212 and its opposing clip 263 makes physical and electrical connection with the data signal conductor 213 so that the opposing clips 262, 263 apply a holding force to the edge 215 of the structure 211. Another pair of opposing clips (occluded from view and not shown) is also provided wherein one of the clips makes physical and electrical connection with the voltage reference conductor 212 and the other of the clips makes physical and electrical connection with the data signal conductor 213 so that the opposing clips also apply a holding force to the edge 215 of the structure 211.
It is known that when the length of the connector 100 is a multiple of one half the wavelength of the data signals passing through the data signal conductors of the connector 100, then the frequency of the data signals is at a resonant frequency. At or near the resonance, the insertion-loss-to-crosstalk ratio (ICR), a key parameter for determining the connector's performance, is significantly degraded. Thus, if the resonant frequency falls within or near the operating frequency range of data signals being communicated by the connector 100, the performance of the connector 100 may be significantly degraded.